What Will Happen if I Consume Too Much Calcium?

It was worse for those with a high dietary consumption of calcium who in addition took calcium supplements, either in the form of multivitamins or calcium tablets. Their all-cause mortality was 2.57 times that of those with a moderate consumption of calcium. According to the authors, “among women with a high dietary intake of calcium, the addition of calcium increased the risk of death in a dose dependent fashion.” This is evidence that the relationship was not just that of statistical association, but of causation.

Interestingly, the women who took calcium supplements, whether as multivitamins or as calcium tablets, were likely to live healthier lifestyles than those who did not: to exercise more, eat more healthily, etc. In other words, they were probably more inclined to do things for the sake of their health, even those things that in the event turn out not to be so good for the health. As Hegel said in another connection, the Owl of Minerva takes wing by night.

There was something I did not quite understand, or at least that surprised me, in the figures given by the authors of this paper. I quote:

11,944 women died; of these women, the underlying cause of death was cardiovascular disease in 3862 ischaemic heart disease in 1932, and stroke in 1100.

Now cardiovascular disease encompasses, among other things, ischaemic heart disease and stroke, that is to say 3032 of the 3862 cardiovascular deaths, leaving 830 others. I think this large latter number will come as a surprise to any doctor.

Nevertheless, the paper is potentially important, especially if it is replicated elsewhere (for you should never put your faith in one study alone, especially when it depends upon the manipulation of complex statistics), for it suggests that the benefit of calcium supplementation is not only the medical equivalent of an urban myth, but a dangerous one at that.